All four of the corpses found near a Long Island beach in December were young prostitutes who advertised their services on the Internet and were likely slain by a serial killer, authorities said yesterday.

After identifying one of the bodies as a Maine hooker last week, officials revealed that the three other skeletons found wrapped in burlap bags at Gilgo Beach were all Craigslist escorts who were killed shortly after meeting their slayer for sexual trysts.

Using DNA evidence, the victims were identified as Maureen Brainard-Barnes, 25, of Norwich, Conn.; Amber Lynn Costello, 27, of North Babylon; and Melissa Barthelemy, 24, of Buffalo.

Megan Waterman, 22, of Maine, was identified last week.

The killer’s last known victim, Costello, went missing from North Babylon only five months ago on Sept. 2. Waterman was last seen at a Hauppauge Holiday Inn on June 6 of last year, Barthelemy went missing from The Bronx on July 12, 2009, and Brainard-Barnes vanished from Manhattan in July 2007.

“I think it fits within the known definition of what a serial killer would be,” said Suffolk County District Attorney Thomas Spota, adding that more than one culprit could be involved.

Barthelemy, who moved from Buffalo to New York to become a stripper and prostitute, was reported missing on July 18, 2009. The NYPD confirmed that her mother and sister received calls from her daughter’s cellphone just days after she went missing.

“Do you know what your sister does for a living?” the male caller asked, according to Barthelemy’s mother. “Your sister’s a whore, don’t be like your sister.”

Barthelemy’s mother said her daughter first traveled to New York with her rapper boyfriend and decided to stay. She promised she would use the money earned from her stripping and prostitution to one day return to Buffalo.

Waterman traveled to Hauppauge last June with her boyfriend and pimp, Akeem Cruz, 20, of Brooklyn, and vanished after leaving the hotel. Cruz is currently in prison in Maine on a drug rap.

Norwich cops said that Brainard-Barnes left her Connecticut home for New York City on July 12, 2007, and has not been heard from since.

Originally published by SELIM ALGAR and JOHN DOYLE.